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4

The refrigerant widely used in domestic refrigerators is

A. Ammonia

B. Carbon dioxide

C. Sulphur dioxide

D. R-12

Correct Answer :

D. R-12


Related Questions

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4

In chemical dehumidification process,

A. Dew point temperature decreases

B. Wet bulb temperature decreases

C. Dry bulb temperature increases

D. All of these

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4

A certain refrigerating system has a normal operating suction pressure of 10 kg/cm gauge and condensing pressure of about 67 kg/cm. The refrigerant used is

A. Ammonia

B. Carbon dioxide

C. Freon

D. Brine

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4

The emissivity of a polished silver body is __________ as compared to black body.

A. Same

B. Low

C. Very low

D. High

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4

In a vapour compression system, the condition of refrigerant before passing through the condenser is

A. Saturated liquid

B. Wet vapour

C. Dry saturated vapour

D. Superheated vapour

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4

The condensing pressure due to the presence of non-condensable gases, as compared to that actually required for condensing temperatures without non-condensable gases,

A. Will be higher

B. Will be lower

C. Will remain unaffected

D. May be higher or lower depending upon the nature of noncondensable gases

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4

The wet bulb temperature during sensible heating of air

A. Remains constant

B. Increases

C. Decreases

D. None of these

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4

An infinite parallel planes with emissivities e₁ and e₂, the interchange factor for radiation from surface 1 to surface 2 is given by

A. (e₁ + e₂)/ e₁ + e₂ - e₁e₂

B. 1/e₁ + 1/e₂

C. e₁ + e₂

D. e₁e₂

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4

Which of the following refrigerant is highly toxic and flammable?

A. Ammonia

B. Carbon dioxide

C. Sulphur dioxide

D. R-12

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4

The leakage in a refrigeration system using Freon is detected by

A. Halide torch

B. Sulphur sticks

C. Soap and water

D. All of these

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4

For unsaturated air, the dew point temperature is __________ wet bulb temperature.

A. Equal to

B. Less than

C. More than

D. None of these

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4

Mass flow ratio of NH₃ in comparison to Freon12 for same refrigeration load and same temperature limits is of the order of

A. 1 : 1

B. 1 : 9

C. 9 : 1

D. 1 : 3

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4

Most air cooled condensers are designed to operate with a temperature difference of

A. 5°C

B. 8°C

C. 14°C

D. 22°C

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4

In a bootstrap air evaporative cooling system, the evaporator is provided

A. Between the combustion chamber and the first heat exchanger

B. Between the first heat exchanger and the secondary compressor

C. Between the secondary compressor and the second heat exchanger

D. Between the second heat exchanger and the cooling turbine

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4

In a refrigeration cycle, the flow of refrigerant is controlled by

A. Compressor

B. Condenser

C. Evaporator

D. Expansion valve

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4

A good refrigerant should have

A. High latent heat of vaporisation and low freezing point

B. High operating pressures and low freezing point

C. High specific volume and high latent heat of vaporisation

D. Low C.O.P. and low freezing point

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4

For large tonnage (more than 200 TR) air-conditioning applications, the compressor recommended is

A. Reciprocating

B. Rotating

C. Centrifugal

D. Screw

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4

Under cooling in a refrigeration cycle

A. Increases C.O.P

B. Decreases C.O.P

C. C.O.P remains unaltered

D. Other factors decide C.O.P

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4

The relative humidity is defined as

A. The mass of water vapour present in 1 m3 of dry air

B. The mass of water vapour present in 1 kg of dry air

C. The ratio of the actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature and pressure.

D. The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure

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4

The higher temperature in vapour compression cycle occurs at

A. Receiver

B. Expansion valve

C. Evaporator

D. Compressor discharge

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4

The refrigerant after condensation process is cooled below the saturation temperature before throttling. Such a process is called

A. Sub-cooling or under-cooling

B. Super-cooling

C. Normal cooling

D. None of these

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4

The process, generally used in winter air-conditioning to warm and humidity the air, is called

A. Humidification

B. Dehumidification

C. Heating and humidification

D. Cooling and dehumidification

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4

The capillary tube is not used in large capacity refrigeration systems because

A. Cost is too high

B. Capacity control is not possible

C. It is made of copper

D. Required pressure drop cannot be achieved

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4

The refrigerant used for absorption refrigerators working on heat from solar collectors is a mixture of water and

A. Carbon dioxide

B. Sulphur dioxide

C. Lithium bromide

D. R-12

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4

The index which correlates the combined effects of air temperature, relative humidity and air velocity on the human body, is known as

A. Mean radiant temperature

B. Effective temperature

C. Dew point temperature

D. None of these

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4

The colour of the flame of halide torch, in case of leakage of Freon refrigerant, will change to

A. Bright green

B. Yellow

C. Red

D. Orange

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4

Air refrigerator works on

A. Reversed Carnot cycle

B. Bell Coleman cycle

C. Both (A) and (B)

D. None of these

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4

Rick up the incorrect statement

A. Lithium bromide used in vapour absorption cycle is non volatile

B. Lithium bromide plant can't operate below 0°C

C. A separator is used in lithium bromide plant to remove the unwanted water vapour by condensing

D. Concentration of solution coming out of lithium bromide generator is more in comparison to that entering the generator

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4

Nusselt number (NN) is given by

A. NN = hl/k

B. NN = μ cp/k

C. NN = ρ V l /μ

D. NN = V²/t.cp

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4

The operating temperature of a cold storage is 2°C. The heat leakage from the surrounding is 30 kW for the ambient temperature of 40°C. The actual C.O.P. of refrigeration plant used is one fourth that of ideal plant working between the same temperatures. The power required to drive the plant is

A. 1.86 kW

B. 3.72 kW

C. 7.44 kW

D. 18.6 kW

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4

The change in evaporator temperature in a refrigeration cycle, as compared to change in condenser temperature, influences the value of C.O.P.

A. More

B. Less

C. Equally

D. Unpredictable